1. Field of the Invention
The present invention relates to a novel crystalline form of a triethylamine salt of a substituted thiazolylacetic acid compound which is useful as an intermediate for preparing cross-linked glycopeptide-cephalosporin antibiotics. This invention also relates to processes and intermediates for preparing the crystalline form.
2. State of the Art
U.S. Pat. No. 6,974,797 B2 discloses a compound of the formula:
This compound is a synthetic intermediate used in the preparation of a cross-linked glycopeptide-cephalosporin antibiotic. The compound is described as a tan solid which can be purified by extraction to remove residual succinimide (Example A, Step 4; Column 29, lines 07 to 37). This compound is not described as being crystalline.
Although this intermediate compound is useful for preparing cross-linked glycopeptide-cephalosporin antibiotics, it would be advantageous to provide an intermediate compound that is in crystalline form. Crystalline intermediates are advantageous because impurities are typically removed or substantially reduced during the crystallization process thereby resulting in an intermediate having improved purity. Moreover, crystalline materials often have improved storage stability and better handling properties compared to non-crystalline materials. Accordingly, it would be desirable to provide an intermediate useful for preparing cross-linked glycopeptide-cephalosporin antibiotics which is in crystalline form.